Lab 9 Electric Circuits Objectives: Learn to build electric Circuits. Using voltmeter and Ammeter to measure voltage and current. Understand current and voltage relationships when resistors are in series and parallel. Apply Ohm's law to solve current, voltage or resistance. Simulation link: https://phet.colorado.edu/sims/html/circuit-construction-kit-dc/latest/circuit-construction-kit-dc_en.html Introduction to the simulation and Ohm's law: The simulation has a component selection pane on the left with various circuit components such as wires, batteries and bulbs. On the right side is an ammeter to measure current and a voltmeter to measure voltage. Below that is a battery shown pictorially and as an electric symbol. The circuit components can be viewed pictorially or as symbols by selecting one of these two. The convention in circuit analysis is for current to flow out of the positive terminal of the battery and into the negative terminal of the battery. In actuality, the flow of electrons is the opposite of this. On the top right of the screen you can select to see the flow of current. The relationship between current (1), voltage (V), and resistance (R) is given by Ohm's Law V= IR or I = V/R. Resistance value of components can be edited by a tap on the component. Procedure and Calculation: 1 point per question Part I Getting familiar with the simulation and symbols. Select 'Labels' and 'Values'. Build the circuit in figure1 to get familiar with the PhET. The circuit in Fig 1 contains a battery connected to a bulb and resistor in series through a switch. Redraw this circuit in the box with the corresponding electric component symbols as shown below. Connecting wire -WWw- Resistor Lamp or light globe Battery Switch Voltmeter Electric Electric motor bell Figure 1 A pictorial representation of a circuitPart It Simple circuit Let's start with a simple circuit a 9v battery is connected to a resistor (10 52) through a switch. A voltmeter can be used to measure the vottage across any component in the circuit as shown. (Tap the battery to edit voltage) Questions Answers What do you expect the voltage across the resistor to be? Construct the circuit in gure 2 and measure the voltage across the resistor GIN'41: Tap on the resistor and change the resistance to 2052. Now measure the voltage across the resistor. 4:. If the battery was changed into a 12V battery what would the voltage across the resistor be? 5 Return the resistance value back to 10 2 so that the circuit looks like gure 2 again. Now what is the current owing through this circuit? Calculate it using Ohm's law. 6 Tap the battery and ip the polarity of the battery in the edit pane. Select 'Show Current' on the top right and observe the ow. Return the battery polarity to the original orientation and observe the current flow again. What do you notice? Part III Resistors in Series Connect two 10 Q resistors in series with . . a 9V battery as shown in figure 3, -" . 1:: lm.a=s=j m Questions Answers What do you expect the voltage across terminals A and C to be? Using the voltmeter measure voltages: VAC, Vita. Vac. Calculate the effective resistance in the series circuit 44:9 center: 0 Calculate equivalent current 1 Is the current owing into the rst and second resistor the same? You can check your answers by connecting the ammet'er rst at the negative terminal of the battery, and then at terminal C, and naily between 8&0. Part IV Two dissimilar resistors in Series Using two different resistors to construct a circuit as shown in Figure 4. 4 10.0 0-. -20 0 0- C Voltage Figure 4 Series circuit with dissimilar resistors # Questions Answers Will the current be the same through each resistor? Will both resistors have the same voltage across them? Measure VAC , VAB , and VBC O - U - A - W - N - Calculate equivalent resistance Calculate equivalent current V - Move the ammeter to between the resistors and measure the current at different points in the circuit, what is it? Part V Resistors in Parallel Connect two resistors in parallel with a 9V 9.0 V battery as shown in figure 5. R1 10.0 0 R2 20.0 0 Voltage ? Figure 5 resistors in parallel # Questions Answers 18 What is the voltage across each resistor? Measure VR1 and VR2 19 Use Ohm's law, calculate current through R1 and R2 20 Calculate total current through battery using 11+12 21 Measure total current by connecting the ammeter next to the battery as shown22 Which figure has the smallest equivalent resistance, figure 4 or 5? 23 What would be the same for resistors in parallel? (V, I, R) 24 What would be the same for resistors in series? (V, I, R) Screenshot